1. Field of the Invention
The present invention relates to a grommet which is installed on a wire harness for an automobile and mounted in the penetration hole of an automobile body panel, and to a method of installing the grommet in the panel.
2. Background of the Invention
When a wire harness is wired from the engine compartment of an automobile to passenger compartment, a grommet 1 made of a rubber or an elastomer is conventionally mounted on the outside of the wire harness W/H, as shown in FIG. 6 and FIGS. 7(A)-(C). Water proof properties and dust proof properties for preventing the invasion of water, dust and the like through the penetration hole 3 from the engine compartment side to the passenger compartment are imparted by inserting the wire harness W/H provided with the grommet 1 into the penetration hole 3 of the automobile panel 2 which separates the engine compartment (X) and the passenger compartment (Y) and mounting the grommet 1 around the peripheral edge of the penetration hole 3.
The grommet 1 is provided with a small diameter tube portion 1a into which the wire harness W/H is inserted in a fitted condition, and is provided with an enlarged diameter tube portion 1b which continues in a conical tube shape from one end of the small diameter tube portion 1a. A recessed portion 1c for hooking on the automobile is provided on the outer peripheral surface of the enlarged diameter tube portion 1b. The recessed portion 1c is inserted into the penetration hole 3 of the automobile body panel 2 to install the grommet 1 on the automobile body panel 2. The thickness of the portion where the recessed portion 1c for hooking on the automobile body panel is provided increases in order to enhance the hooking force at installation, and the recessed portion 1c is made deeper. In other words, the height from the bottom surface 1d of the recessed portion 1c to the edges of both of the side walls 1e and 1f is increased.
For example, as shown in FIG. 6, the depth H1 of the peripheral wall 1e in the edge opening side is set at 8.6 mm, and the depth H2 of the peripheral wall 1f at the edge of the portion 1g, where the peripheral face is slanted while increasing in thickness from the small diameter tube portion in the opposite side, is set at 6.1 mm. Further, the dimension L1 from the peripheral wall 1e in the edge opening side to the opening edge 1h is set at 9 mm, and the dimension L2 of the sloping portion in the opposite side is set at 16.6 mm.
As shown in FIG. 7, the grommet 1 is conventionally inserted from the enlarged diameter tube portion side 1b, from the engine compartment (X) to the passenger compartment (Y) through the penetration hole 3. The entire grommet 1 is first pushed into the passenger compartment (Y) while inwardly deforming the outer peripheral portion containing the recessed portion 1c, which is larger than the inner diameter of the penetration hole 3. Then, the wire harness W/H is pulled back toward the engine compartment (X), and the recessed portion 1c is mounted in the penetration hole 3 to install the grommet 1 on the automobile body panel 2. Namely, the installation of the grommet 1 on the automobile body panel 2 is carried out by two motions, i.e., by first pushing the grommet into the passenger compartment (Y) from the engine compartment (X) and then pulling it back into the engine compartment. The reason why the recessed portion 1c is mounted in the automobile body panel 2 by first pushing the grommet into the passenger compartment and then pulling it back again is that the peripheral wall of the penetration hole 3 cannot be smoothly and positively mounted in the recessed portion 1c between the peripheral wall 1f having a smaller depth when the grommet is pushed in from the peripheral wall 1e having a greater depth.
With the recent rapid increase in parts mounted in an automobile, parts are arranged on both sides of the automobile body panel 2 where the above-mentioned grommet 1 is installed. When the grommet 1 is installed on the automobile body panel 2 as described above, and the entire grommet 1 is first pushed into the car passenger compartment from the engine compartment side., it becomes difficult to provide sufficient space for accepting the grommet when pushed into the passenger compartment. Further, although the grommet must be pulled back into the engine compartment after pushing it into the passenger compartment, there is also little or no space available in the engine compartment for carrying out the work of pulling the grommet back into the engine compartment side.
The wire harness W/H is required to be wired from the engine compartment into the passenger compartment from the engine compartment (X) to the passenger compartment (Y) through the penetration hole 3 of the automobile body panel 2, due to requirements of the construction of the automobile and the like. However, as described above, the problem occurs such that the installation method of the grommet by the two motions of pushing it in and pulling it back into the engine compartment, as shown in FIGS. 7(A)-(C) using the grommet 1 of FIG. 6, cannot be adopted due to lack of space.
The present invention was developed considering the above-mentioned problem, and an object is to provide a grommet having a construction such that the grommet can be positively inserted and hooked in the penetration hole of an automobile body panel by a single push-in motion from the engine compartment side, and another object is to provide an installation method for the grommet.
In order to solve the above-mentioned problems, the present invention includes a grommet made of a rubber or an elastomer and is provided with a small diameter tube portion in which a wire harness is inserted in a fitted condition, an enlarged diameter tube portion which continues in a conical tube shape from one end of the small diameter tube portion, and a recessed portion for hooking on an automobile body panel. The recessed portion is provided about the outer peripheral surface of the enlarged diameter tube portion. Furthermore, the height of first and second peripheral walls on opposite sides of the bottom face of the recessed portion is established so that the height of the second side wall of the small diameter tube portion side is about 50% to 35% based on the height of the first side wall on an opening edge side of the enlarged diameter tube portion side. Moreover, the width of the recessed portion between the first side wall and the second side wall is set to be greater than the height dimension of the second side wall, and the second side wall is deformable inwardly into the recessed portion.
The height of the second side wall is more preferably about 45% to 40% based on the height of the first side wall, and the height of the second side wall is preferably about 70% to 60% of the width of the recessed portion. Further, the height of the second side wall is about 70% based on the height of the first side wall in comparison with the conventional grommet shown in FIG. 6, and is about 70% to 100% in either of the grommets conventionally provided. Also, the height of the second side wall is larger than the width of the recessed portion in the conventional grommet shown in FIG. 6.
Further, in the grommet of the present invention, the axial length of the sloping portion of the second side wall is about 90% to 40% of the axial length of the first side wall to the opening end of the enlarged diameter tube portion, and preferably is about 85% to 70%. In comparison, the axial length of the sloping portion is 150% to 200% in the conventional example shown in FIG. 6.
Further, the second side wall of the grommet of the present invention slopes toward the first side wall from the bottom face side to the upper edge side, and a groove portion is provided on the inner peripheral surface of the enlarged diameter tube portion at a position where the second side wall protrudes from the outer peripheral face of the enlarged diameter tubular portion. The second side wall can easily slope toward the recessed portion side by forming the above shape.
Furthermore, a lip protrudes at the outer edge and from an intermediate portion of the first side wall, and a lip also protrudes at the bottom face of the recessed portion. When the lips are thus formed on the first side wall and the bottom face of the recessed portion, the coherence of the peripheral edge of penetration hole of the automobile body panel fitted in the recessed portion can be enhanced, and the sealing properties can be improved.
In another aspect of the present invention, a method of installing the above-mentioned grommet is provided. The grommet is inserted into the penetration hole having a burring of the automobile body panel, from the small diameter tube portion side. The second side wall is deformed inwardly into the recessed portion by engagement with the burring, and by passing the second side wall through the penetration hole of the automobile body panel. The second side wall is then restored after passing through the penetration hole, so that the peripheral edge of the penetration hole of the automobile body panel is received within the recessed portion between the first side wall and the second side wall, whereby the grommet is installed on the automobile body panel with only a single push-in motion.
Specifically, the grommet is pushed into the penetration hole having a burring from the engine compartment to the passenger compartment on the automobile panel, from the small diameter tube portion side, and is installed on the automobile body panel by only a single push-in motion.
As described above, the grommet can be passed through the penetration hole by only pushing the second side wall to deform inwardly the same because the height of one peripheral wall (the second side wall) of the recessed portion on the insertion side of the automobile body panel to the penetration hole is reduced. Since the height of the first side wall is at least double or more, a moderate sense of feel occurs, and the grommet can be positively hooked by a single push-in motion. Accordingly, even if there is no space on both the engine compartment side and the passenger compartment side, the installation of the grommet on the automobile body panel can be carried out without any difficulty.
Further, the above-mentioned sloping portion continues to the second side wall and is continued to the linear position of the small diameter tube portion side which is at about the same elevation as the bottom surface of the recessed portion. Since the outer diameter of the sloping portion is larger than the inner diameter of the penetration hole, it is necessary to reduce the diameter of the second side wall by deformation when the second side wall is passed through the penetration hole. Therefore, the length of the sloping portion decreases by a half or more in comparison with the length of the sloping portion of a conventional grommet, and the height is also decreased by about a half. Accordingly, the second side wall is very easily deformed inwardly during insertion into the penetration hole. In other words, the second side wall is easily bent. As a result, workability can be improved because a smaller operational force during pushing in is required.
Furthermore, with respect to the hooking retention force against the automobile body panel, the second side wall is restored to an original condition from a inwardly deformed condition by bending from the bottom face side of the recessed portion during installation in the penetration hole, and is hooked on the peripheral edge of the penetration hole. Thus, since it becomes a nearly locked condition, a hooking retention force similar to a conventional one can be obtained even though the height of the second side wall is reduced.
According to another aspect of the present invention, a grommet is configured for installation in an aperture by a single push-in motion. The grommet includes a small diameter tube portion through which a wire harness is extendable in a tightly interfitted condition, an enlarged diameter tube portion including a conical tube portion is connected to one end of the small diameter tube portion, and a recessed portion is provided for hooking in the aperture. The recessed portion is provided about an outer peripheral surface of the enlarged diameter tube portion, and includes a first peripheral side wall on an opening edge side of the enlarged diameter tube portion and a second peripheral side wall on an opposite side of a bottom surface of the recessed portion and on the small diameter tube portion side. Furthermore, a height of the second side wall is smaller than a height of the first wall, and a width of the recessed portion between the first and second walls is greater than the height of the second wall, and the second side wall is deformable inwardly into the recessed portion during installation.
In other aspects of the present invention, the grommet may be configured so that the height of the second wall is about 50% to 35% of the height of the first side wall. Additionally, the second side wall may include a sloping portion, extending from an upper edge of the second side wall, that reduces in diameter from the height of the second wall to about the same level as the position of a bottom surface of the recessed portion, and an axial length of the sloping portion may be about 90% to 40% of an axial length of the first side wall to an opening end of the enlarged diameter tube portion.
In a further aspect of the present invention, the grommet may be configured so that the second side wall includes a sloping portion that slopes upwardly toward the first side wall side from the small diameter tube side to an upper edge of the second side wall, and a groove portion may be provided on an inner peripheral surface of the enlarged diameter tube portion at a position where the second side wall protrudes from an outer peripheral face of the enlarged diameter tubular portion.
According to another aspect of the present invention, a method of installing a grommet is provided. The grommet includes a small diameter tube portion through which a wire harness is extendable in a tightly interfitted condition, an enlarged diameter tube portion including a conical tube portion connected to one end of the small diameter tube portion, and a recessed portion for hooking in the aperture. The recessed portion is provided about an outer peripheral surface of the enlarged diameter tube portion, and the recessed portion includes a first peripheral side wall on an opening edge side of the enlarged diameter tube portion and a second peripheral side wall on an opposite side of a bottom surface of the recessed portion and on the small diameter tube portion side. The recess is configured so that a height of the second side wall is smaller than a height of the first wall, and a width of the recessed portion between the first and second walls is greater than the height of the second wall, and the second side wall is deformable inwardly into the recessed portion during installation. The method includes installing the grommet on a wire harness, inserting the grommet into a penetration hole having a burring, from the small diameter tube portion side, deforming the second side wall inwardly into the recessed portion by pushing the second side wall with the burring, and passing the second side wall through the penetration hole, and restoring the second side wall after passing through the penetration hole so that the peripheral edge of the penetration hole is received in the recessed portion between the first side wall and the second side wall, whereby the grommet is installed in the penetration hole with only a single push-in motion.
The method of installing the grommet may also include configuring the grommet so that the height of the second wall is about 50% to 35% of the height of the first side wall. Additionally, the second side wall may include a sloping portion, extending from an upper edge of the second side wall, that reduces in diameter from the height of the second wall to about the same level as the position of a bottom surface of the recessed portion, and an axial length of the sloping portion may be about 90% to 40% of an axial length of the first side wall to an opening end of the enlarged diameter tube portion.
In a further aspect of the present invention, the method of installing the grommet may also include configuring the grommet so that the second side wall includes a sloping portion that slopes upwardly toward the first side wall side from a the small diameter tube side to an upper edge of the second side wall, and a groove portion may be provided on an inner peripheral surface of the enlarged diameter tube portion at a position where the second side wall protrudes from an outer peripheral face of the enlarged diameter tubular portion.